Work done in bringing a charge from infinite.

1. The problem statement, all variables and given/known data
3 charges, A,B, and C are located at the vertices of an equilateral triangle. Point P is at the center of the triangle, and is 8 cm from each charge. Charge A is +7 μC. Charge B is +6 μC. Charge C is -10μC. If a 4μC charge is brought from infinite to point P, how much work was done in moving this charge to point p.

2. Relevant equations
W=fd
F= Kq1q2/r2

3. The attempt at a solution
I think you're supposed to use w=fd. And i can get the force with coulombs law, but i don't understand the charge being brought from infinite.

1. The problem statement, all variables and given/known data
3 charges, A,B, and C are located at the vertices of an equilateral triangle. Point P is at the center of the triangle, and is 8 cm from each charge. Charge A is +7 μC. Charge B is +6 μC. Charge C is -10μC. If a 4μC charge is brought from infinite to point P, how much work was done in moving this charge to point p.

2. Relevant equations
W=fd
F= Kq1q2/r2

3. The attempt at a solution
I think you're supposed to use w=fd. And i can get the force with coulombs law, but i don't understand the charge being brought from infinite.